External appearance is one of the inspection methods that are done by comparing images of an inspected object with a reference image. In case of one or two sides imaging e.g., wafers or Printed Circuit Boards an image is captured from a perpendicular view or from a below view for inspection, which are simple tasks.
In the case of a six-faced object, the procedure is more complicated. Such an inspection is needed for many products and some of these products are very small or in large quantities. For instance, there is a need to inspect the whole sides of electrical objects that are used in microelectronic production (Ceramic Capacitors, Chips and Resistors); a wide range of defects such as dimensional measurements, ceramic defects and termination defects can be recognized by using automatic optical inspection systems.
Systems that use imaging of the overall sides of an object were disclosed in U.S. Pat. No. 4,912,318 “inspection Equipment for Small Bottles” and U.S. Pat. No. 4,219,269 “External Appearance Inspection System” both assigned to Kajiura et al. additionally, these systems have some shortcomings.
Objects such as but not limited to small capacitors can be damaged during the inspection process or before the inspection process. Dirt as well as objects pieces can jam an inspection device.
The measurement of absolute electrical characteristics of objects, such as capacitors is a relatively long process that limits the throughput of the inspection process.
There is a growing need to provide efficient systems and methods for inspecting objects.